← Triangles: angle sum, exterior angle and Pythagoras lesson New set →

Class 7 Maths Worksheet: Triangles

Maths worksheets lesson 53: Triangles: angle sum, exterior angle and Pythagoras · Set 381 · 40 sums
TalentJR

The method (Inside 180, outside the sum): Angle sum: ∠A + ∠B + ∠C = 180°. Exterior angle = sum of the two interior opposite angles. Right-angled triangle: longest side² = side² + side² (3, 4, 5 and 5, 12, 13 are famous sets). Sides can make a triangle only if the two shorter sides add up to more than the longest side.

NameDateTime takenScore ___ / 40
  1. 1.Can a triangle have sides of 12 cm, 5 cm and 3 cm? (a) No (b) Yes
  2. 2.The longest side of a right-angled triangle is 25 cm and one of the other sides is 7 cm. How long is the third side (in cm)?
  3. 3.In a right-angled triangle, one of the other two angles is 60°. What is the third angle (in degrees)?
  4. 4.In triangle ABC, angle A = 52° and angle B = 30°. What is angle C (in degrees)?
  5. 5.The two interior opposite angles of a triangle are 78° and 34°. What is the exterior angle (in degrees)?
  6. 6.The angles of a triangle are in the ratio 1 : 3 : 5. What is the biggest angle (in degrees)?
  7. 7.Can a triangle have sides of 8 cm, 17 cm and 9 cm? (a) Yes (b) No
  8. 8.The longest side of a right-angled triangle is 25 cm and one of the other sides is 24 cm. How long is the third side (in cm)?
  9. 9.The two shorter sides of a right-angled triangle are 16 cm and 12 cm. How long is the longest side (in cm)?
  10. 10.The longest side of a right-angled triangle is 17 cm and one of the other sides is 15 cm. How long is the third side (in cm)?
  11. 11.Can a triangle have sides of 8 cm, 4 cm and 6 cm? (a) Yes (b) No
  12. 12.In a right-angled triangle, one of the other two angles is 54°. What is the third angle (in degrees)?
  13. 13.The angles of a triangle are in the ratio 2 : 7 : 9. What is the smallest angle (in degrees)?
  14. 14.An exterior angle of a triangle is 101°. One of its two interior opposite angles is 21°. What is the other one (in degrees)?
  15. 15.The angles of a triangle are in the ratio 4 : 5 : 6. What is the biggest angle (in degrees)?
  16. 16.In an isosceles triangle, the angle between the two equal sides is 30°. What is each of the other two angles (in degrees)?
  17. 17.An exterior angle of a triangle is 107°. One of its two interior opposite angles is 76°. What is the other one (in degrees)?
  18. 18.An exterior angle of a triangle is 104°. One of its two interior opposite angles is 72°. What is the other one (in degrees)?
  19. 19.The two shorter sides of a right-angled triangle are 7 cm and 24 cm. How long is the longest side (in cm)?
  20. 20.The two shorter sides of a right-angled triangle are 12 cm and 5 cm. How long is the longest side (in cm)?
  21. 21.The angles of a triangle are in the ratio 3 : 5 : 7. What is the smallest angle (in degrees)?
  22. 22.Can a triangle have sides of 4 cm, 12 cm and 13 cm? (a) Yes (b) No
  23. 23.An exterior angle of a triangle is 57°. One of its two interior opposite angles is 32°. What is the other one (in degrees)?
  24. 24.The two interior opposite angles of a triangle are 54° and 55°. What is the exterior angle (in degrees)?
  25. 25.In an isosceles triangle, the two equal angles are 64° each. What is the third angle (in degrees)?
  26. 26.In a right-angled triangle, one of the other two angles is 49°. What is the third angle (in degrees)?
  27. 27.Can a triangle have sides of 8 cm, 12 cm and 10 cm? (a) Yes (b) No
  28. 28.In a right-angled triangle, one of the other two angles is 17°. What is the third angle (in degrees)?
  29. 29.The two interior opposite angles of a triangle are 56° and 31°. What is the exterior angle (in degrees)?
  30. 30.In triangle ABC, angle A = 86° and angle B = 50°. What is angle C (in degrees)?
  31. 31.The angles of a triangle are in the ratio 1 : 2 : 6. What is the smallest angle (in degrees)?
  32. 32.Can a triangle have sides of 2 cm, 10 cm and 10 cm? (a) No (b) Yes
  33. 33.An exterior angle of a triangle is 93°. One of its two interior opposite angles is 44°. What is the other one (in degrees)?
  34. 34.The two shorter sides of a right-angled triangle are 10 cm and 24 cm. How long is the longest side (in cm)?
  35. 35.In a right-angled triangle, one of the other two angles is 11°. What is the third angle (in degrees)?
  36. 36.The two shorter sides of a right-angled triangle are 15 cm and 36 cm. How long is the longest side (in cm)?
  37. 37.In a right-angled triangle, one of the other two angles is 71°. What is the third angle (in degrees)?
  38. 38.The angles of a triangle are in the ratio 3 : 4 : 5. What is the biggest angle (in degrees)?
  39. 39.Can a triangle have sides of 12 cm, 9 cm and 22 cm? (a) Yes (b) No
  40. 40.In a right-angled triangle, one of the other two angles is 69°. What is the third angle (in degrees)?

Answer key

  1. No
  2. 24
  3. 30
  4. 98
  5. 112
  6. 100
  7. No
  8. 7
  9. 20
  10. 8
  11. Yes
  12. 36
  13. 20
  14. 80
  15. 72
  16. 75
  17. 31
  18. 32
  19. 25
  20. 13
  21. 36
  22. Yes
  23. 25
  24. 109
  25. 52
  26. 41
  27. Yes
  28. 73
  29. 87
  30. 44
  31. 20
  32. Yes
  33. 49
  34. 26
  35. 79
  36. 39
  37. 19
  38. 75
  39. No
  40. 21

Free maths worksheets lessons, practice and worksheets at talentjr.in/maths-worksheets